4 binders cost $7.92. Which equation would help determine the cost of 14 binders?
Answer: There are several equations that could help determine the cost, each with a slightly different approach. We know the cost of 4 binders. We want to know the cost of 14 binders. We can write the numbers of binders as a proportion: $\dfrac{4}{14}$ We know 4 binders costs $7.92. We can let $x$ represent the unknown cost of 14 binders. The proportion of these costs can be expressed as: $\dfrac{\$7.92}{x}$ The cost changes along with the number of binders purchased, and so the two proportions are equivalent. $\dfrac{4}{14} = \dfrac{\$7.92}{x}$